Brake release valve



L. A. MAJNERI BRAKE RELEASE VALVE April 18, 1950 2 Sheets-Sheet l INVENTOR.

LUDWIG A.MAJNER| Filed Dec. 11, 1944 ATTORNEYS April 18, 1950 L. A. MAJNERI 2,504,859

BRAKE RELEASE VALVE Filed Dec. 11,1944 2 Sheets-Sheet 2 INVENTOR.

LUDWIG A. MAJNERI ATTORNEYS Patented Apr. 18, 1950 vBRAKE RELEASE VALVE Ludwig A. Majneri, Grosse Pointe, Mich., assignor to The Warner Aircraft Corporation, Detroit, Mich., a corporation of Michigan Application December 11, 1944, Serial No. 567,657

3 Claims.

This invention relates generally to valve assemblies and refers more particularly to a valve assembly capable of being installed in a hydraulic braking system for accelerating release of the brake or brakes in the system.

One of the principal objects of this invention is to provide a valveassernblyhaving means for by-passing fluid from the hydraulic brake actuator to a storage chamber immediately upon release of the brake applying means. Thus the fluid pressure in the hydraulic brake actuator is practically instantaneously dropped sufficiently to allow the brake friction means to disengage from the braking surface on the brakedrum, and as a result, dragging of the brake by delayed release is eliminated.

Still another object of this invention is to provide a valve assembly which is instantaneously responsive to a drop in pressure in the hydraulic actuator resulting from releasing the brake applying means to not only by-pass fluid from the actuator to the chamber but to alsoreturn fluid from the hydraulic actuator to the fluid reservoir usually forming a part of hydraulic braking systems and to enable return of the fluid in the chamber to the reservoir after the brake is completely released.

The foregoing as well as other objects will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawing wherein: p c

Figure 1 is a diagrammatic view of a braking system embodying the valve assembly forming the subject matter of this invention.

Figure 2 is a sectional view through the brake releasing valve shown in Figure, 1.. V I

Figure 3 is a view similar to Figure 2 showing the valve in a different position; and c V Figure 4 is a cross sectional view taken substantially on the plane indicated by the line 4-4 of Figure 2. V

In Figure l of the drawing I have shown a typical hydraulic braking system of the type usually employed in connection with aircraft, although it will be understood from the following description that the invention may beused in practically any type of hydraulic braking system wherein it is desirable to provide instantaneous release of thebrake or brakes in the system.

In general, the braking system shown in Figure loomprises a brake IE! having a brake drum 1 I and having brake friction means 12 suitably supported within the drum. The brake friction means l2 are adapted to be'moved outwardly face on the drum H by a hydraulic actuator l3. The hydraulic actuator I3 may be of any accepted construction and is usually supported within the drum I l between adjacent ends of the friction means.

Operation of the brake in is initiated by a pressure producing device or master cylinder M. The master cylinder It may also be of any suitable design and is shown in Figure 1 as comprising a cylinder I 5 having a piston It supported therein for sliding movement in opposite directions. The piston I6 is normally urged in an upward direction in the cylinder [5 by a spring 11 and is moved downwardly against the action of the spring by a manually operable control i8. The upper end of the cylinder communicates with a reservoir [9 through the medium of a conduit 2|], and the lower end of the cylinder i5 communicates with a power valve 2!. I

The power valve 2i selected for the purpose of illustration is of the same type shown in my co pending application Serial No. 546,347, filed July 24, 1944, and now abandoned. Briefly, the power valve comprises a casing 22 having an intake port 23 communicating with the lower end of the master cylinder l5 through the medium of a conduit 24 and having an outlet port 25 which communicates with the actuator [3 through the medium of a supply line 26. In addition, the casing 22 has a second inlet port 21 which communicates with an accumulator 28 and is also provided with a second outlet port 29 which communicates with the reservoir l8. It may be pointed out at this time that the accumulator 28 contains braking fluid which is maintained at a relatively high pressure by a pump 30.

into irictional engagement with the braking sur A valve 3| is supported in the casing 22 for movement in opposite directions. The valve 3| is normally urged to the position shown in Figure 1 by a spring 32 act ng upon the lower end of the valve. When the valve is in this position the ports 25 and 29 are connected in order to establish communication between the hydraulic actuator I 3 and the reservoir l8. s

The valve 3| is moved downwardly against the action of the spring 32 by fluid pressure entering the port 23 from the master cylinder 4. When the valve is in its lowermost position, the port 23 is closed and the port 2'! is opened to the port 25 to supply fluid under pressure from the accumulator 28 to the brake actuator it. As a result the actuator l3 moves the brake friction means l2 outwardly against the braking surface onthedrumll. p g

The releasing valve forming the subjectmatter of this invention is connected in the line 26 between the power valve 2| and the hydraulic brake actuator 3. This releasing valve is indicated in Figure 1 by the reference character 33 and comprises a casing 34 open at opposite ends for respectively receiving the fittings 35 and 36. Suitable O-rings 31 are provided for sealing the joints between the .fittings and casing. The fitting 35 has a port 38 which is connected to the line 23 or power valve 2|, and the fitting 36 has a port 39 which is connected to a storage chamber A, to be more fully hereinafter described. The casing 34 is provided with a third port 49 intermediate the ports 38 and 39 for connection to the hydraulic actuator l3.

As shown in Figures 2 and 3 of the drawing, the casing 34 is also formed with a cylindrical chamber 4| intermediate the ends thereof .in direct communication with the port 48. In additio the casing is formed with reduced cylin drical portions 42 and 43 at opposite ends of the chamber 4|. A valve member 44 is movable in opposite directions in the casing 34 and the opposite ends of the valve member alternatively slidably engage the walls of the cylindrical portions 42 and 43. The intermediate portion of the valve member 44 is slidabl-y supported by a partition 45 in the chamber 4|, and suitable openings 45 are formed in the partition to enable free flow of fluid throughout chamber 4|. Also suitable O-rings .41 are respectively mountedon opposite ends of the valve member 44 to prevent the escape of fluid under pressure past theseends when the latter respectively occupy positions in the cylindrical portions 42 and 43 of the casing.

The valvemember 44 is formed with two vertically spaced chambers48 and 49 separated by a transverse wall 59 having a port therethrough surrounded at the upper end with a comically shaped valve seat 52. The chamber 49 communicates with the chamber 4| in all positions of the valve member 44 through a plurality of circumferentially spaced ports 53. However,

communication between the chambers 48 and v 4.9 is controlled by a valve member 54 inthe form of a sleeve closed at the bottom by a wall 55.and having a conically shaped surface 56 engageable with the correspondingly shaped seat 52 to close the port.5|. The valve 54 is normally urged to the position shown in Figure 3 of the drawing wherein the'surface 56 on the valve is held inengagement with the seat 52 by .a relatively weak spring 51 located within the valve 54 with the lower end engaging a shoulder 58 on the valve and with the upper end engaging a washer 59 held in position in the valve 44 by a snap .ring 60.

The pper end of valve 54 is open to receive fluid passing downwardly into the casing 34 through the port 38, and theside walls of the valve 54 are provided with ports 6| which communicate with the chamber 48. Thus it will be noted that while thevalve 54 is carried by the valve member 44 it operates entirely independently of the .latter. In this connection attention isalso called to the fact that the valve 44 isrncrmally urged to the position shownin Figure 2 of the drawing by a spring 62 supported in the casing below the valve member 44. As shown, the top of the spring engages the bottom of the valve member 44, and the lower end of the spring abuts a shoulder 53 onthe fitting 3.6. It follows from the above-that the springfifi mally urges the valve member 44 to the position r' by the spring shown in Figure 2 oi. the drawing wherein the upper end of the valve member 44 extends into the portion 42 of the chamber and engages a shoulder 64 formed by the bottom of the fitting 35. In this position the lower end of the valve member 44 assumes a position in the chamber 4| above the reduced portion 43 and communication is established between the chamber 4| and the port 39 through the end portion 43 of the casing 34.

Referring now to the operation of the valve assembly and assuming that the master cylinder H has been operatedto supply fluid under pressure tothe line 26 through the power valve 2 it will be noted that this fluid under pressure enters the valve casing 34 through the port 38. The fluid entering the port 38 passes into the valve 54 and acts on the wall 55 to move the valve member 44 to the position shown in Figure 3 of the drawing wherein the upper end of the valve member 44 assumes a position in the chamber 4| slightly below the cylindrical portion 42 of the casing 34. In this position of the valve member 44 fluid is free to pass into the chamber 4| and through the port 40 to the hydraulic actuator |3 to apply the brake I0. Fluid is prevented from escaping into the lower cylindrical portion of the casing 34by reason of the fact that the-lower end of the valve member occupies a position in the portion 43 and is sealed by the lower -O-ring 41. Assuming now that the operator releases the control 8, it will be noted that the piston IS in themaster cylinder is returned to its-inoperative position in the cylinder As a resultoi this movement of the'piston l6, fluid in the master cylinder escapes into the reservoir l9 through the conduit .28. Also the pressure in the power valve 2! is reduced to such an extent as to permit the spring 32 to move the valve member 3| to the position shown in Figure 1 of the drawing wherein the ports 25 and 29 are connected to establish com munication between the hydraulic brake actuator |3 and reservoir l9. As a result of the above, the pressure in the brake actuator i3 is reduced.

As the pressurein the line 25 or actuator 53 drops, the valve member 44 is moved upwardly in the casing 34 by the spring 52 to the position shown in Figure 2-of the drawing. As the lower end of the valve member 44 moves out of the lower end 43 of the casing, fluid from the hydraulic actuator |3is immediately lay-passed into the chamber A through the port 39 and the brake I9 is instantaneously released.

Releasing of the brake is further'accelerated by opening the valve 54. As shown in Figure 2 of the drawing, fluid returning through the port 49 enters the chamber 49 in the valve member 44 and moves the valve 54 upwardly against the relatively weak spring 51. As a result fluid flows into the chamber 48.through the port 5| and into the valve 54 through the ports 6|. Inasmuch as the top of the valve 54 is open, it-follows that the fluid passes through the port 38 into the line 26 and back to the reservoir |9 through the power valve 2|. It has been stated above that fluid from the actuator I3 is by-passed by the valve 33 to a storage chamber A. This chamber comprises a tank Bidivided into two compartments 6'! and 68 by a flexible diaphragm 69. The compartment 68 communicates directly with the port 39 of the releasing valve, 33 through a relatively short conduit 18,;and the compartment 61 is equipped with an air valve 1| through which air may be introduced into the compartment 61 to initially load the diaphragm. The pressure provided in the compartment 61 is considerably lower than the brake applying pressure, but is sufiicient to return practically all of the fluid in the compartment 68 to the line 26 or reservoir l9 after the brake friction means I2 is completely released from the brake drum ll.

What I claim as my invention is:

l. A valve assembly comprising a casing having a chamber provided with spaced first and second ports, a third port intermediate the first and second ports, a valve member slidably supported in the chamber, parts on the valve member responsive to movement of the valve member in one direction to close communication between the first and third ports and to establish communication between the second and third ports, said parts being responsive to movement of the valve member in the opposite direction to open communication between the first and third ports and to close communication between the second and third ports, a chamber in the valve member having a fluid connection with the third port at all positions of said valve member and communicating with the first port, and a valve element slidably supported in the valve member and having fluid pressure responsive means for closing communication between the first port and chamher in the valve member in response to fiuid pressure admitted through the first port.

2. A valve assembly comprising a casing provided with a chamber having reduced cylindrical portions spaced from each other by an enlarged cylindrical portion, a first port in one of the reduced portions and a second port in the other reduced portion, a third port in the enlarged portion, a valve member supported in the chamber for sliding movement and having axially spaced portions alternately movable into and out of the reduced portions of the chamber upon movement of the valve member in opposite directions, means on the valve member adjacent opposite ends thereof respectively engageable with the reduced portions of the chamber to close communication between the third port and the first and second ports, a chamber in said valve member having a fiuid connection with the enlarged intermediate portion of the chamber in the casing at all positions of said valve member and communicating with the first port, and a valve element carried by said valve member and having fluid pressure responsive means for closing communication between the valve member chamber and first port in response to fluid pressure admitted to the casing chamber through the first port.

3. A valve assembly comprising a casing provided with a chamber having reduced cylindrical portions spaced from each other by an enlarged cylindrical portion, a first port in one of the reduced portions and a second port in the other reduced portion, a third port in the enlarged portion, a valve member supported in the chamber for sliding movement and having the opposite ends alternately movable into and out of the reduced portions of the chamber upon sliding movement of the valve member in opposite directions to respectively close communication between the third port and said first and second ports, a chamber in the valve member having a fluid connection with the third port through the intermediate enlarged portion of the casing chamber at all positions of said valve member and open to communication with the first port, a valve element slidably supported in the valve member chamber and having fluid pressure responsive means for closing communication between the first port and valve member chamber in response to fluid pressure admitted to the casing through the first port, spring means normally urging the valve member to a position wherein the first port is closed and the second port is open thereby, and spring means resisting Opening movement of the valve element by the fiuid under pressure in said valve member chamber.

LUDWIG A. MAJNERI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,645,798 Callan Oct. 18, 1927 1,726,102 Forman Aug. 27, 1929 2,024,628 Craig Dec. 17, 1935 2,248,350 Campbell July 8, 1941 2,300,694 Overbeke Nov. 3, 1942 2,358,228 Hoof Sept. 12, 1944 2,362,945 Stephens Nov. 14, 1944 2,445,505 Ashton July 20, 1948 

